There is also no doubt about the antiquity and Indo-European origins of the Slavic god Perun, the god of thunder and lightning. The name Perun derives from an Indo-European root perk, perg or per, meaning - to strike, and is directly associated with a striking thunder­bolt.80 In Indian mythology there was a weather god, Parjanya, whose domain was thunder storms and monsoons. This deity, who also makes things grow, like Perun, is associated with cattle.81 Moreover, among the Baits, a thunder god Perkunas was one of the major deities.82 There is a close conceptual relationship between the foregoing and thunder-asso­ciated gods of other Indo-European people, such as: Celtic Taranis; Greek Zeus and Ger­manic Thor/Donar.83 Independent developments separated Indo-European beliefs, but cer­tain common concepts were preserved. For example, in Germanic mythology the goddess Fjórgynn is the mother of the thunder god Thor. Taking into consideration that in Ger­manic languages the original Indo-European "p" changed into "f", her name clearly appears related to the stem perg.M In Hittite mythology the stone monster Ullikummi, who fights the weather god Tešub, is a son of the major god Kumarbi and a rock, a goddess called Perunas or Pirunaš.85 Unfortunately, Hittite mythology is so mixed up with Semitic and non-Indo-European beliefs that the similarity of name with Parjanya or Perun may be only a coincidence. On the other hand it may reflect a common Indo-European tradition shared with the Germanic people.

Further support for the antiquity of the Perun-like deity in Eastern Europe comes from Mordvinian mythology. In pre-Christian times, the Mordvins, who are an Ugro-Finnic people of the middle Volga basin, worshipped a thunder god called Purginepaz.86 This is a clear borrowing from the Indo-European mythology. However, it was not borrowed from the Slavs, as their Eastern branch did not penetrate the middle Volga in pre-Christian times. While at the same time the rootpurg in Purginepaz suggests some relation with the Baltic perk in Perkunas, the only plausible explanation being that the Mordvins borrowed the concept and the god's name from the Fatyanovo culture of the second half of the second millennium B.C.E. The Fatyanovo culture emerged in the Eastern Baltic area and spread along the Volga and Oka as far as the Ural mountains. The physical anthropology, and the strong cultural affiliation of the Fatyanovo complex with the Kurgan and later Baltic cul­tures, indicates that they were Indo-European people. They were not Baits, and probably not Balto-Slavic people either, but rather culturally and linguisticaly ancestral to both.87 Whatever the case, this shows that the concept of a Perun-like deity was common amongst the Old European population of Eastern Europe in the middle of the second millennium B.C.E. This in turn clearly indicates a continuity of this common Indo-European concept.

The evidence for the notion of a thunder god among the Slavs is relatively plentiful, with his worship first mentioned among the Southern Slavs. According to the mid-6th century Byzantine historian Procopius:

"For they ( Slavs ) believe that one god, the maker of the lighting, is alone lord of all things, and they sacrifice to him cattle and all other victims".88

There is no doubt that this account refers to Perun. The account does not imply that the Slavs were monotheists, but rather that Perun gained prominence among the Southern Slavs, whose religion evolved into henotheism. There is also evidence that in the mythology of non-Slavic Albanians, there was a thunder god known as Perěndi. Again, this is no doubt a borrowing from the Southern Slavs.89
As a consequence of the relatively early Christianisation of the Southern Slavs, there are no more direct accounts in relation to Perun from the Balkans. Nevertheless, as late as the first half of the 12th century, in Bulgaria and Macedonia, peasants performed a certain ceremony meant to induce rain. A central figure in the rite was a young girl called Perperuna, a name clearly related to Perun. At the same time, the association of Perperuna with rain shows conceptual similarities with the Indian god Parjanya. There was a strong Slavic pen­etration of Albania, Greece and Romania, between the 6th and 10th centuries. Not surpris­ingly the folklore of northern Greece also knows Perperuna. Albanians know Pirpiruna, and also the Romanians have their Perperona.90 Also, in a certain Bulgarian folk riddle the word perusan is a substitute for the Bulgarian word гърмотевица (grmotevitsa) for thun­der.91 Moreover, the name of Perun is also commonly found in Southern Slavic toponymy. There are places called: Perun, Perunac, Perunovac, Perunika, Perunićka Glava, Peruni Vrh, Perunja Ves, Peruna Dubrava, Perunuša, Perušice, Perudina and Perutovac.92

In addition, the Eastern Slavs, promised to uphold treaties with the Byzantines by invoking Perun in 907, 945 and 971. The Perun idol was already standing in Kiev by 945, when prince Igor swore to be true to the treaty at the shrine.93 Therefore, either Vladimir did not erect it or only enlarged the shrine.
There are more accounts and other evidence showing that the cult was widespread among the ordinary people and in various forms survived christianization. It is worth not­ing certain passage in The Russian Primary Chronicle. This stated that when the Perun idol and its sanctuary was destroyed, the people cried,94 -while, according to the Chronicle of Novgorod, assault on the Perun shrine in Novgorod caused serious uprising and bloody fighting in the city.95 Surely, both cases implied that it was a well established people's cult and not exclusively a domain of the elite.
The survival of Perun's worship well into the Christian era is also well attested. The following accounts strongly demonstrate the popularity of the cult among the ordinary people. In a Russian apocrypha of the 12th century, known as Хождвне Богуродицы по мукам (Hozhdyene Bognroditsipo mukám), idols of Perun and other gods were mentioned:
"And they made gods out of the devils Troyan, Khors, Veles and Perun, and they
worshipped these evil devils".96

Furthermore, a 14th century source known as Слово Григория (Slovo Grigoriya - The Word of Gregory), says that in remote areas pagans still prayed to Perun.97 In the late 18th century Russia, an ecclesiatic ruling had forbidden the singing of Christian prayers in front of an oak tree.98 It has to be remembered that the oak tree was closely associated with the cult of Perun (oak tree worship will be discussed later). Also, an interesting custom was reported near Novgorod, as late as the early 12th century. Here many travellers or boatsmen, sailing the Volkhov river, would cast a coin into the water, at the spot where the Perun shrine was excavated in the 1950's."

Finally, after Christianization the cult merged and was transformed into veneration of Saint Elias. This happened most likely because of the Old Testament, which credited Saint Elias with the ability to bring rain and thunderstorms. Thus, through these means, an obscure Christian saint became a major celebrity in Eastern Slavic Orthodoxy. In the later Christian iconography of Saint Elias, he appears like Perun traversing the sky in the chariot of fire or riding on the horse. He has also been associated with thunders, arrows and oaks.100 In the early 20th century, in the north-east of Russia, the following celebration was re­ported. On the 20th of July, Saint Elias' day, a cow was slaughtered and the meat prepared by males. It was then distributed in the church and eaten by the whole congregation. This custom, evidently not being Christian, resembles the sacrificial killing of an animal and the communal consumption of the meat.101

The veneration of St. Elias with its mixture of pagan and Christian elements is one of the best arguments for the purely Slavic character of Perun and of the cult being wide­spread among all sections of Eastern Slavic society. Put simply, if Perun was only a deity of the elite and was elevated to prominence at Kiev only for a few years, ordinary people would not have retained the cult for centuries. Neither would the Orthodox Church be forced to accept and tolerate certain evidently pagan beliefs and practices. The name of Perun also appears in Eastern Slavic toponymy. The most famous place is Peryn' near Novgorod, where the remnants of an open site shrine were unearthed by archaeologists,102 and there was a place on the Dneper known as "Perun's Shoal".103

Perun was also a deity of the Western Slavs, although the cult did not show up so prominently. In all Slavic languages, except Polish and Kashubian, the term for thunderbolt is grom. The term is known to the Poles but more often they call it "piorun", a word clearly deriving from the name of Perun. In Silesia, even today, people say typieronie!, which in free­lance translation means " you bastard!". The older Poles' saying of dissatisfaction, do pioruna!, could be translated as "by thunder!". It sounds like nonsense, but if we substitute the old meaning it would be "by Perun!". Very close to the familiar "by Jove!".104 Similar sayings have survived among the Kashubians in the form of na perónu! and ty peronie!. It is good to note that in Kashubian, thunder or lighting is called parón not perón,105 indicating that the original saying refers to the deity rather than to thunder. In Moravian and Slovakian folklore there are spells using the term purom or hrom (original Slavic "g" replaced by "h" in Ukrainian, Czech, Slovak and High Serbian languages) interchangeably for thunder.106 Furthermore, the Slovaks would say parom do teba or do paroma, meaning "may Perun strike you" and "by Perun!", respectively.107 Among the now almost extinct Polabian Slavs of eastern Germany, a deity-called Porenutius (Porenut) was reported on Rugen island by a Danish chronicler of the turn of the 13th century Saxo Grammaticus.108 Some scholars have interpreted the name as a corrupted form of Perun. However, this interpretation is not uniformly accepted- Another deity called Proue was mentioned by Helmold as being worshipped in the 12th century near Oldenburg in Wagrien. Its idol stood in an enclosed sanctuary situated in an oak grove. Sacri­fices of cattle and sheep, and sometimes humans were performed for this deity, and once a week the tribal court and assembly was held there.109 Again it has been postulated that the name Proue is a corruption of Perun, taking into consideration that in another version of the chronicle, known as the Stettin manuscript, it appears as Prone.'10 Whatever the case, Proue's association with oaks and with cattle sacrifice indicates close conceptual links with a Perun-like deity. Toponymic evidence from the Polabian lands is a harbour of Prohn (Por) in the Tribsee region opposite Rugen island, recorded in the earliest source as Perun."1

Nonetheless, the strongest evidence for the antiquity of the Perun cult, as well as its universality among all the Slavs, and all sections of the Slavic society, comes from the western extreme of Slavdom. In the region of Hanoverian Wendland, west of the Elbe river in Germany, a Polabian Slavic language survived till the end of the 18th century. Those Slavs called Thursday a Perěndan - meaning literally a "day of Perun"."2 Evidently, these people were aware that the name for Thursday in German Donnerstag means "day of thunder",(deriving from a continental Germanic war god Donar). However, instead of sub­stituting the Polabian word grom for the thunder they used the word peren. Clearly, the term peren, as in the Polish language, derives from the name Perun.